Guide wire structure for insertion into an internal space

ABSTRACT

A method is described of inserting guide wires into a lumen, for example into the human gastrointestinal tract. A guide wire structure is employed which comprises at least two guide wires each having a leading end portion which terminates in a leading end, the guide wires being connected to one another by a junction at or adjacent their leading ends, the guide wires have a first position in which the leading end portions are substantially parallel to one another, a second position in which the leading end portions are curved, and a third position in which at least one of the leading end portions forms a loop. The guide wire structure is steered through the gastrointestinal tract by selectively advancing or retracting a single guide wire or advancing more than one guide wire simultaneously, according to the path which is required to be followed.

This application claims priority to and incorporates by reference GreatBritain Patent Application Serial No. 0307715.3 filed Apr. 3, 2003 andhaving the same title.

This invention relates to a guide wire structure for insertion into aninternal space defined by a wall. The invention is particularlyconcerned with a guide wire structure which can be inserted into aninterior space within a human or animal body. More particularly, itconcerns a guide wire device which can be inserted into, and movedalong, a lumen within the body of a human patient, for example withinthe gastrointestinal (GI) tract of a human patient.

A physician typically accesses and visualizes tissue within a patient'sgastrointestinal (GI) tract with a long, flexible endoscope. For theupper GI, a physician may insert a gastroscope into the sedatedpatient's mouth to examine and treat tissue in the esophagus, stomach,and proximal duodenum. For the lower GI, a physician may insert acolonoscope through the sedated patient's anus to examine the rectum andcolon. Some endoscopes have a working channel, typically about 2.5-3.5mm in diameter, extending from a port in the handpiece to the distal topof the flexible shaft. A physician may insert medical instruments intothe working channel to help diagnose or treat tissues within thepatient. Physicians commonly take tissue biopsies from the mucosallining of the GI tract using a flexible, biopsy forceps through theworking channel of the endoscope.

Insertion of a flexible endoscope, especially into the colon, is usuallya very time-consuming and uncomfortable procedure for the patient, evenwhen sedated with drugs. A physician often needs several minutes to pusha flexible endoscope through the convoluted sigmoid, descending,transverse, and ascending portions of the colon. The physician maydiagnose and/or treat tissues within the colon either during insertionor removal of the endoscope. Often the flexible endoscope “loops” withinthe colon, such as at the sigmoid colon or at the splenic flexure of thecolon, so that it becomes difficult to further advance the endoscopealong the colon. When a loop is formed, the force exerted to push thescope stretches the mesentery and causes pain for the patient. Dependingon the anatomy of the patient and the skill of the physician inmanipulating the flexible endoscope, some portions of the colon may beunexamined, thus increasing the risk of undiagnosed disease.

Given® Engineering LTD, Yogneam, Israel, sells a device in the U.S.called the M2A™ Swallowable Imaging Capsule. The device contains a tinyvideo camera, battery, and transmitter. It is propelled through thegastrointestinal tract by natural peristalsis. The device is currentlyused for diagnostic purposes and passes through the intestinal tractwith a velocity determined by the natural, peristaltic action of thepatient's body. PCT publication No. WO 01/08548 describes aself-propelling device adapted to travel through a passage having wallscontaining contractile tissue. The applicants disclose that the deviceis particularly useful as an enteroscope and may also carry objects suchas feeding tubes, guide wires, physiological sensors or conventionalendoscopes within the gut. A summary of other alternative to pushendoscopy can be found in “Technical Advances and Experimental Devicesfor Enteroscopy” by C. Mosse, et al, published in GastrointestinalEndoscopy Clinics of North America, Volume 9, Number 1, January 1999:pp. 145-161.

Guide wires have been used to aid the introduction of catheters andother instruments into many sites in the human body. Many medicalapplications and specific designs of guide wires have been forcardiovascular use. There are, however, specific challenges relates tothe use of guide wires in the GI tract, as opposed to the vascularsystem. Thus, the bowel is more tortuous, softer and generally of largerdiameter. Furthermore, in the case of the small intestine and the colon,these are longer than most arteries or veins. It is an object of anaspect of the invention to provide a guide wire structure which iscapable of being advanced along the GI tract, and which, underappropriate conditions and with sufficient medical skill, can be usedsafely even when passing through complex looped formations of smallintestine.

According to the present invention, there is provided a guide wirestructure for insertion into an interior space defined by a wall, theguide wire structure comprising at least two guide wires each having aleading end portion which terminates in a leading end, the guide wiresbeing connected to one another at or adjacent their leading ends, theguide wires have a first position in which the leading end portions aresubstantially parallel to one another, a second position in which theleading end portions are curved, and a third position in which at leastone of the leading end portions forms a loop. It is to be understoodthat, as used herein, the term “loop” does not necessarily denote acomplete loop, but also includes a partial loop. It is also to beunderstood that the two guide wires (or, where there are more than twoguide wires, any two of the guide wires) may be in the form of acontinuous piece of guide wire material whose two ends are broughttogether where the connection is formed.

A primary purpose of the above structure is for insertion into aninterior space within a human or animal body, for example into the GItract of a human patient. It is believed that the guide wire structureof the present invention should be capable of being negotiated throughthe small intestine or colon, and may allow the delivery of endoscopicdevices even to relatively inaccessible parts of the gut such as thececum (accessed via the anus) and the distal jejunum and ileum (accessedvia the mouth).

In one embodiment of the invention there are precisely two guide wiresconnected to one another at their leading ends. For many purposes, twowires are believed to be sufficient. However, in some circumstances morethan two wires may be appropriate, and the present invention envisagesthat the guide wire structure may have three wires, four wires, or evenmore than four wires.

The invention is described further below with reference to theaccompanying drawings, in which:

FIG. 1 a shows an embodiment of guide wire structure according to thepresent invention in the condition which it tends to adopt when not inuse;

FIG. 1 b shows the structure of FIG. 1 a when one of its guide wires isadvanced rightwardly and the other is held steady;

FIG. 1 c shows the structure of FIG. 1 a after further righthand advanceof one of the guide wires;

FIG. 2 shows an example of a pattern of markings which may be providedon the guide wires to indicate their relative position to a physician;

FIG. 3 a to 3 c show a guide wire structure according to the inventionadvancing into the colon;

FIG. 4 shows diagrammatically a handle for use in controlling movementof the guide wires;

FIGS. 5 a and 5 b show successive stages in the use of the guide wirestructure of the present invention in conjunction with a bias tube;

FIGS. 6 a and 6 b show successive stages in the use of a cuttingcatheter to sever the junction between two guide wires;

FIG. 7 shows an embodiment of the invention which comprises two guidewire structures arranged in parallel;

FIGS. 8 a to 8 c illustrate diagrammatically the use of a guide wirestructure according to the present invention, which has a pivotaljunction portion; and

FIG. 9 shows yet another guide wire structure according to the presentinvention.

The structure of FIG. 1 a comprises a first guide wire 1 and a secondguide wire 2, the wires 1 and 2 being connected to one another by ajunction 3 formed at the leading ends of the wires 1 and 2. Although thejunction 3 is shown as being at the leading ends, it could alternativelybe adjacent the leading ends. The length of the junction need be no morethan is necessary to hold the leading ends securely together side byside. Depending on the nature of the junction, a length of as little as5-10 mm may be sufficient, though a greater length may sometimes bepreferable.

The guide wires 2 and 3 can be made of the materials conventionally usedfor guide wires, for example straight stainless steel wire, coiledstainless steel wire, glass fiber, a plastics material, or nitinol.Conveniently, a guide wire has a floppy tip, i.e. a leading end portion,typically 4-5 cm in length, of greater flexibility than the remainder ofthe guide wire, in order to reduce the risk of the leading end of theguide wire causing damage to the wall of the lumen through which it ispassing. Where two such conventional guide wires are joined together toproduce the guide wire structure of the present invention, it will ofcourse be these floppy tips, or parts thereof, which are joinedtogether. Preferably, the length of the junction is less than the lengthof the floppy tips, so that some length of floppy material remains whichis unaffected by the junction.

The whole or part of each of the guide wires may be coated to reduce itscoefficient of friction, as is done with conventional guide wires. Forexample, guide wires can be coated with a low friction material such assilicone, or with a hydrophilic material which becomes slippery in usein a patient, or with both a low friction material such as silicone andhydrophilic material applied over the low friction material.

The junction 3 can be formed in any desired manner, provided theresulting leading end of the guide wire structure is not such as todamage the wall of the GI tract or other body lumen, nor cause unduepain when in contact therewith. For example, the junction can be made bygluing or welding the leading end portions together and, preferably,then covering those portions with heat shrink tubing. Alternatively, theend portions could be held together by having a metal band crimped on tothem, optionally enclosed by a cover made of a softer material.

It is not essential for all the guide wires, or both the guide wires, asthe case may be, to be of material which would normally be regarded asguide wire material. For example, in the case of a guide wire structureconsisting of just two guide wires, one of the guide wires may be madeof a thread, which is joined to the other guide wire by being tied toit.

Yet another possibility would be to start with a single guide wire oftwice the required length and fold it sharply back on itself, forexample by crimping the folded wire adjacent the fold, so that itbecame, in effect, a pair of guide wires joined at the fold. A guidewire structure having an even number n of guide wires greater than twocould be formed by folding half that number of guide wires.

The principle of operation of the guide wire structure can be seen bycomparing FIGS. 1 b and 1 c with FIG. 1 a. FIG. 1 b shows the result ofadvancing the guide wire 1 rightwardly, as indicated by the arrow,whilst holding the guide wire 2 still. As indicated in FIG. 1 b, thiscauses the distal region of the guide wire structure to curve in adirection so that the advanced guide wire 1 is on the outside of thecurve and the still guide wire 2 is on the inside of the curve.Continued advancement of guide wire 1 beyond the position illustrated inFIG. 1 b, whilst continuing to hold guide wire 2 steady, results in theformation of a loop in an end region of guide wire 1. This isillustrated in FIG. 1 c, where the loop is denoted by reference numeral4.

To enable the physician to easily advance one of the guide wires whilekeeping the other still, the guide wires are preferably received, attheir ends remote from the junction 3, in a handle which can be moved upand down the guide wires as they are advanced and retracted. The handleshould allow precise regulation of the relative lengths of the two guidewires. It should also allow the introduction of the various catheters,imagers and other accessories, discussed in more detail below, givingaccurate information on their relationship to the junction 3. The handlemay be provided with a reversible motor drive which enables both guidewires to be driven. The motor drive itself may provide data to enablethe user to monitor the lengths of the guide wires which have been fedforward.

An example of a handle is illustrated in FIG. 4. The illustrated handle40 comprises a pistol grip 41 within which is mounted a pair of electricmotors 42 (of which one is shown) powered either by a battery 43 or amains supply 44. The motors are controlled by respective finger controls45, one for each motor, each control having forward, reverse and stoppositions. Each motor provides drive, via a respective gear, showndiagrammatically at 46, to a respective belt or chain drive 47, each ofwhich propels a respective guide wire 48 forwardly (or backwardly). Aswitch 47 a is provided to cause the driving belts or chains to moveaway from the wires, to allow the wires to be released, for example atthe conclusion of a procedure. A lock mechanism 49 is provided to attachthe handle 40 to a catheter or to an accepting channel of an endoscope,through which the guide wire is to be driven. The guide wires are storedin a coiled plastics tube 50, either with both wires side by side in asingle tube or each in its own tube. This has the benefit of keeping theguide wires clean, and avoiding the risk of their trailing on to thefloor. Under some conditions this storage facility may be omitted.

The combined effect of the forms of behaviour illustrated in FIGS. 1 band 1 c enables the guide wire structure of the present invention toperform in a highly advantageous manner. Thus, causing the structure tobecome curved, as shown in FIG. 1 b, enables the physician to steer theleading end of the structure round bends in the lumen through which thestructure is being advanced. The ability to form a loop, as illustratedin FIG. 1 c, enables the guide wire structure to adopt as configurationin which it can be safely advanced along the lumen, without unduediscomfort for the patient.

Furthermore, the presence of a loop at the leading end of the structurerather than the tip of a single wire, makes the structure more likely tofollow the main course of the lumen, and less likely to inadvertentlyenter branches off it. Thus, in the case of the gut, there will be amuch reduced tendency to enter, for example, diverticulae or the orificeof the appendix. However, the fact that the loop is not permanentlypresent, and can be eliminated by putting the structure into theconfiguration shown in FIG. 1 a, means that the structure can easily,and without damage to itself, be passed along a very narrow passageway.It can therefore be passed, for example, along a channel of an endoscopeor down a catheter, as is described further below. Also, when the guidewire structure is not in an endoscope or catheter, but is advancingdirectly along a patient lumen, it is not always desirable to do so witha loop at the front (for example if it has to pass through a smallopening). Under such circumstances the guide wire structure is allowedto revert to the straight form shown in FIG. 1 a with both guidewiresbeing advanced aligned and in unison.

FIGS. 3 a to 3 c show diagrammatically, and by way of example,successive stages in advancing the guide wire structure of the inventionalong a colon 30. It is shown being introduced in conjunction with acatheter 31 within which the whole guide wire structure is slidablyreceived. The individual guide wires are denoted as w₁ and w₂.Advancement takes place by alternately:

-   -   (a) pushing one wire forward while holding the other still; and    -   (b) pushing the catheter forwards as far as the position shows        in FIG. 3 c, or even somewhat further.

It is desirable in endoscopic procedures to avoid, or at least reduce,the use of X-ray imaging to monitor what is taking place. With this inmind, the guide wires are preferably each provided with a pattern ofmarkings, distributed along their length, to indicate how far eachindividual guide wire has been inserted. One such pattern in shown inFIG. 2. As shown there, a pattern of markings in a given colour, andsimilar in nature to a bar code, is spaced along a first length (L₁),and then repeated along successive lengths (of which only L₂ is shown)each time in a different colour. Each of the lengths could convenientlybe of the order of 10 cm. This provides a method by which the physiciancan easily see which of the guide wires is the further advanced, and byhow much, and enable him, for example, to make the inserted lengthsequal and thus eliminate any curve (FIG. 1 b) or loop (FIG. 1 c). Ofcourse, many other patterns of marking, for example numerals or letters,could be used instead of that illustrated, which is given only as anexample.

Additionally, or instead, the guide wire structure can be provided withother forms of position indication. It is known to provide aconventional guide wire with a series of miniature electricallyconductive coils which surrounded the guide wire and are spaced alongits length, the coils being connected to a source of electrical current,whereby each coil becomes a miniature electromagnet. Such coils can beprovided on the guide wires used to form the guide wire structure of thepresent invention. A sensing device outside the patient is used todetect the position of the coils within the patient, and therebydetermine the location of the guide wires.

The path of the guide wire structure can be influenced by the use of acatheter, which can be passed over one or both of the two guide wires,when there are precisely two, or over one, some, or all of the guidewires, when there are more than two. In one particularly advantageousembodiment the catheter has a curved tip, which allows the applicationof torque to bias the forward motion of the guide wire (or wires) overwhich it passes in any given direction. The use of a catheter in thisway is illustrated in FIGS. 5 a and 5 b. FIGS. 5 a and 5 b show a pairof guide wires 51 and 52 joined at a junction 53. Guide wire 51 isreceived within a catheter 54, referred to herein as a bias tube, theleading end portion of which is so formed as to have a curvature in it.The guide wire 51 with the bias tube, and the guide wire 52, are bothreceived within an outer catheter 55. The ends of the catheters 51 and52 remote from their tips emerge from the catheter 55 to allow them toselectively advance and retract. The end of the bias tube 54 remote fromthe curved end thereof emerges from the outer catheter 55 at the user'send. As can be seen by comparing the state shown in FIG. 5 a with thesubsequent state shown in FIG. 5 b, in advancing both the guide wires,but advancing guide wire 51 more than guide wire 52, the bias tube helpsto ensure that the combined guide wire structure curves in the desireddirection. If it were desired to cause the structure to advance in someother direction, this could be achieved by twisting the catheter 55about its longitudinal axis, thus altering the positions of the guidewires relative to the lumen in which they are being advanced.

The purpose of the guide wire is, as its name indicates, to act as aguide for some other element. Accordingly, when the guide wire structureof the present invention is in place some other element is then passedover it.

As in the case of a catheter used to influence the path of a guide wirestructure during passage of the guide wire structure along a lumen, acatheter introduced subsequently can pass over one or both of the guidewires, when there are precisely two, or over one, some, or all of theguide wires, when there are more than two. When the catheter is passedover both, or all, the guide wires, as the case may be, the leading endof the catheter will be free to pass beyond the leading end of the guidewire structure once it reaches that point. If the catheter is not passedover both, or all, the guide wires, for example if it is passed overonly one of two interconnected guide wires, the leading end of thecatheter will normally be unable to pass beyond the connection betweenthe guide wires. That may be desirable, for the purpose of ensuring thatthe leading end of the catheter can be brought to a position previouslydefined by the leading end of the guide wire structure. It also has theresult, however, that if the guide wire structure is withdrawn, thecatheter must be withdrawn with it.

If it is desired to enable the leading end of the catheter to passbeyond the end of the guide wire over which it is travelling, or toenable the catheter to remain in position after the guide wire has beenwithdrawn, this can be achieved by providing the leading end of thecatheter with a cutting device. The use of such a catheter isillustrated in FIGS. 6 a and 6 b. FIGS. 6 a and 6 b show guide wires 61and 62 connected by a junction 63 and extending within an outer catheter65. A cutting catheter 64 surrounds one of the guide wires, in this casethe guide wire 61. The catheter 64 has a cutting tip (not visible inFIG. 6 a) which, when the catheter 64 is advanced over the guide wire61, severs the junction 63. FIG. 6 b shows the severing operation partlycompleted.

The cutting catheter comprises a cylindrical cutting member 66 with acircular cutting edge 67 (visible in FIG. 6 b but not in FIG. 6 a)formed at its leading end. When not in use the cutting edge is shieldedby a generally cylindrical sheath 68 which is biased to a forwardprotecting position by a compression spring 69 located between therearward end of the sheath 68 and a stop 70 fixed to the end of thecatheter. When the cutting catheter is pushed forwards, against theforce of the spring 69, as it is in FIG. 6 b, the cutting edge 67emerges from the sheath 68 and severs the junction 63. As soon assevering is completed the spring automatically causes the sheath 68 tomove forwards, covering the cutting edge 67 and preventing it fromharming the patient.

Once a sufficiently large guide wire loop has been formed in, say, thegut, it becomes possible to pull the gut backwards to some extent, usingthe friction between the loop and the wall of the gut. To do this, bothguide wires are pulled backwards in synchronism. This provides a meansfor straightening the gut, and this in turn makes it easier to advancethe guide wire structure further or, indeed, to advance other structures(e.g. endoscopes), and reduces the pain of the procedure, which ismainly caused by stretching nerve endings in the mesentery.

The above described concept of using a guide wire loop to straighten apassageway, e.g. the gut, can be further developed in an embodiment ofthe present invention which employs two guide wire structures operatingin parallel. An example of such an embodiment is shown in FIG. 7. Thiscomprises two parallel catheters 72 a and 72 b, which are preferablyconnected together side by side in such a way as to allow each to movelongitudinally with respect to the other. In the illustrated embodimentthe connection is provided by a T-shaped stud 73 formed on catheter 72 awhich is slidable in a correspondingly shaped passageway 74 formed incatheter 72 b and running longitudinally along it. A single stud may beprovided, or a plurality of studs spaced along the length of catheter 72a, or there may be a continuous stud running along all or part of thelength of catheter 72 a. Catheter 72 a receives a first guide wirestructure 75 a, comprising a pair of wires w₁ and w₂ joined at ajunction 76 a. Catheter 72 b receives a guide wire structure 75 b,comprising a pair of wires w₃ and w₄ joined at a junction 76 b.

The embodiment shown in FIG. 7 can be used in a procedure which employsthe following steps:

-   -   1. Push the combination of catheters 72 a and 72 b into an        appropriate orifice, e.g. the anus in the case of the colon, as        far as they will go.    -   2. Advance wire w₃ as far as the loop which it forms is able to        travel (this is substantially the configuration shown in FIG.        7).    -   3. Pull back on both catheters so that the loop in guide wire        structure 75 b straightens the gut.    -   4. Advance guide wire structure 75 a in its unlooped form, i.e.        wires w₁ and w₂, through the catheter 72 a as far as it will go        (which should be past the loop in guide wire structure 75 b).    -   5. Advance catheter 72 a over w₁ and w₂ so that it is ahead of        catheter 72 b, while catheter 72 a, and the loop extending from        the catheter, hold the gut in position.    -   6. Advance guide wire w₁ or guide wire w₂ so that a loop is        formed in guide wire structure 75 a and advances in the gut.    -   7. Withdraw whichever of wires w₃ and w₄ is the more forward of        the two, so as to eliminate the loop in guide wire structure 75        b.    -   8. Advance catheter 72 b so that it catches up with catheter 72        a.

The above cycle is then repeated until the desired degree of advancementhas been achieved.

A similar cycle of steps can be achieved by a modified form of theembodiment of FIG. 7, in which one or each of the two catheters 72 a and72 b is replaced by a suction catheter. A suction catheter can be usedto effect the above described straightening of the gut by pulling backon it while suction is being applied. The suction is only applied duringthe straightening step. Yet another modification is to replace one ofthe guide wire structures by a soft balloon, which can be inflated toengage the gut wall, and then pulled back to straighten the gut.

Many different devices can be passed over the guide wire structure, andsome examples will now be given.

-   -   (a) A small imager (for example a CCD or CMOS chip) on a        catheter could be passed along the guide wire or guide wires to        the tip. This could optionally be propelled along the guide wire        by a water jet or some other means of tip propulsion to reduce        the force that has to be exerted outside the patient. A source        of white or coloured light could be also introduced by the same        means. This source could be in the form of light emitting diodes        or could use fibre-optics. One of the wires could be optionally        formed out of a fiberoptic bundle. It would be easier to take        the optical signal through a light-weight insulated wire which        could be incorporated into the guide wire or via a separate wire        in a catheter. The imager could then convert the optical        information to radiowaves or microwaves, to send the information        to an aerial attached to, or adjacent to, the exterior of the        patient.    -   (b) A separate soft catheter could be run over the guide wire to        the tip and this could be used to introduce air from a        controlled pump to inflate the viscus. Water for rinsing        purposes could be passed through this catheter or through some        other from a water pump.    -   (c) A catheter could be passed over one of the guide wires,        which would provide a channel through which biopsies could be        performed. This is preferably done after the imager referred to        in (a) above has been placed in position, so that the imager can        be used to view the biopsy procedure. This catheter might have        tip angulation properties.    -   (d) A double lumen catheter could be passed over the double        wire, which might allow the introduction of another wire of        greater stiffness or with a curled tip to allow the movement of        the device in a desired direction.

Once the guide wire, and the imager referred to in (a) above, havereached the desired location, an overtube could be passed, for exampleto the cecum. The guide wire and the imager could then be withdrawn anda conventional endoscope could be passed through the overtube to delivertherapy, for example removing a polyp or cancer.

A conventional endoscope could be introduced into a body lumen bypassing it over the guide wire structure of the present invention.However, a conventional endoscope would normally be too stiff for thisto be possible, and the guide wire structure of the present inventionoffers the possibility of, in effect, constructing an endoscope within apatient. To achieve this, a number of catheters, each providing one ormore of the utilities normally provided a conventional endoscope, aresuccessively passed over one or more of the guide wires, so that resultis an assemblage of these various elements within the patient. Aparticular advantage of proceeding in this way is that the forcerequired to advance each of the individual catheters is substantiallyless than that required to advance a complete conventional endoscope(e.g. a colonoscope or an enteroscopc), since the latter is much stifferand has much greater mass. It is therefore easier for the physician, andless uncomfortable for the patient, and is less likely to cause injuryto the patient. Also, since the endoscope is then assembled element byelement, the endoscope can have those facilities which are required forthe particular patient, and, only those facilities, so that theendoscope is tailored to the requirements of the medical procedure beingcarried out. It will be understood that, for the purpose of allowing insitu assembly of a catheter, the guide wire structure should preferablycomprise more than two guide wires, for example three or four guidewires.

Although a structure having more than two guide wires is particularlyuseful for the purpose discussed above of assembling an endoscope insitu, it may also have value in relation to the procedure forintroducing the guide wire structure into a lumen. This is because thetwo-guide wire structure shown in FIGS. 1 a to 1 c allows curvature inonly one plane, so that steering the structure in three dimensionsrequires the user to twist the structure about its longitudinal axis,for example by using a catheter to which the necessary torque can beapplied. However, if more than two guide wires are provided it ispossible to curve the structure in any plane; three guide wires aresufficient for this purpose.

Attention is now directed to FIGS. 8 a to 8 c, which illustrate the useof a guide wire structure 80 which comprises two guide wires 81 and 82connected by a junction portion 83. As can be seen, the junction portion83 is pivotal about an axis located at the proximal end of the portion83, so that, as shown in FIG. 8 a, it can pivot to such an extent thatit lies flat along the distal end portion of guide wire 81. This isadvantageous in that it makes possible, or makes easier, movement of theportion 83 within a catheter 84, not only where there is no loop present(as in FIG. 8 c) but also when there is (as shown in FIG. 8 a). In thisconnection it is to be understood that the diameter of the catheter 84would actually be substantially greater than that shown in theseFigures. It is also to be understood that instead of being joined by ajunction portion 83 of significant length, as illustrated, the guidewires could alternatively be joined by a junction of substantially nolength, i.e. the ends of the guide wires could be connected by ajunction consisting, at least in substance of just a pivot point.

FIG. 9 shows yet another guide wire structure in which a similarpivoting action can be achieved. This comprises guide wires 91 and 92,having respective floppy tip portions 91 a and 92 a connected to oneanother by a thread or highly flexible wire 93. This thread or wire canbe inserted into the portions 91 a and 92 a, or attached to theirsurfaces.

1. A guide wire structure for insertion into an interior space definedby a wall, the guide wire structure comprising at least two guide wireseach having a leading end portion which terminates in a leading end, theguide wires being connected to one another by a junction at or adjacenttheir leading ends, the guide wires have a first position in which theleading end portions are substantially parallel to one another, a secondposition in which the leading end portions are curved, and a thirdposition in which at least one of the leading end portions forms a loop,wherein the said junction is covered with heat shrink tubing.
 2. A guidewire structure according to claim 1, wherein the said junction is formedby gluing.
 3. A guide wire structure according to claim 1, wherein thesaid junction is formed by welding.
 4. (canceled)
 5. A guide wirestructure for insertion into an interior space defined by a wall, theguide wire structure comprising at least two guide wires each having aleading end portion which terminates in a leading end, the guide wiresbeing connected to one another by a junction at or adjacent theirleading ends, the guide wires have a first position in which the leadingend portions are substantially parallel to one another, a secondposition in which the leading end portions are curved, and a thirdposition in which at least one of the leading end portions forms a loop,wherein the said junction is formed by a metal band crimped over theguide wires.
 6. A guide wire structure according to claim 5, wherein thesaid metal band is enclosed by a cover formed of a softer material.
 7. Aguide wire structure according to claim 1, wherein the number of guidewires is an even number n, and the structure is formed by folding n/2longer guide wires, each having twice the length desired for thestructure, sharply back.
 8. A guide wire structure according to claim 1,wherein the guide wires are provided with marking to enable a user tocompare the lengths of individual guide wires which have beenintroduced.
 9. A guide wire structure according to claim 1, wherein theguide wires are each provided with electrically conductive coils, spacedalong the lengths thereof and connectable to a source of electricalpower, whereby each coil becomes, in use, an electromagnet.
 10. A guidewire structure according to claim 1, wherein the guide wires arereceived in a single catheter.
 11. A guide wire structure according toclaim 1, wherein at least one of the guide wires is received in anindividual catheter.
 12. A guide wire structure according to claim 11,wherein at least one of the catheters is provided at a leading endthereof with a cutter arranged to cut through the said junction.
 13. Aguide wire structure according to claim 12, wherein a shield is disposedat the said catheter leading end, the said shield being movable betweena shielding position in which it surrounds the said cutter, and anon-shielding position in which the said cutter is exposed for use. 14.A guide wire structure according to claim 11, wherein the saidindividual catheter has a leading end portion which is curved.
 15. Aguide wire structure according to claim 1, wherein there are preciselytwo guide wires connected to one another.
 16. A guide wire structureaccording to claim 1, wherein there are more than two wires connected toone another.
 17. A guide wire structure according to claim 16,comprising a first pair of guide wires connected at a first saidjunction and received in a first catheter, and a second pair of wiresconnected at a second said junction and received in a second catheter.18. A guide wire structure according to claim 17, wherein the first andsecond catheters are connected to one another in such a way as to permitlongitudinal movement of each catheter relative to the other.
 19. Aguide wire structure according to claim 18, further comprising anuser-controllable handle for advancing and retracting each of the guidewires.
 20. A guide wire structure according to claim 19, wherein thehandle comprises a guide wire storage device.
 21. A guide wire structureaccording to claim 1, adapted for use where the said interior space isdefined within a human or animal body,
 22. A guide wire structureaccording to claim 21, adapted for use in the human gastrointestinaltract.
 23. (canceled)
 24. A method of inserting the guide wiresstructure of claim 22 into the human gastrointestinal tract, comprisingsteering the guide wires through the tract by selectively advancing orretracting a single guide wire or advancing more than one guide wiresimultaneously, according to the path which is required to be followed.25. A guide wire structure for insertion into an interior space definedby a wall, the guide wire structure comprising at least two guide wireseach having a leading end portion which terminates in a leading end, theguide wires being connected to one another by a junction at or adjacenttheir leading ends, the guide wires have a first position in which theleading end portions are substantially parallel to one another, a secondposition in which the leading end portions are curved, and a thirdposition in which at least one of the leading end portions forms a loop,wherein the said junction is formed by gluing or welding the two wirestogether adjacent the leading ends.